Abstract

The Itmurundy zone of the northern Balkhash area is a Pacific-type orogenic belt. It possesses a complex geological structure and hosts rocks of mantle, accretionary and post-orogenic associations. The volcanic and sedimentary rocks of the accretionary association belong to three suites: Itmurundy (O_1-2), Kazyk (O_2-3) and Tyuretai (O₃-S₁). The suites are separated by tectonic unconformities or faults of three orders: 1) large regional faults; 2) medium faults separating mantle and oceanic accreted rocks; 3) small faults separating packages consisting of oceanic sediments. The Itmurundy Fm. (O_1-2) is the most lithologically variable consisting of oceanic basalt, pelagic chert, hemipelagic siliceous mudstone and siltstone, and trench greywacke sandstone. The packages, each consisting of chert-siliceous mudstone, are separated from each other by 2^nd and 3^rd order faults of probably thrust nature, i.e. they are parts of duplex structures. The presence of duplex structures and the high degree of deformation of Itmurundy Fm. rocks are typical of accretionary complexes. The associations of volcanic and sedimentary rocks under study represent a full section of oceanic plate stratigraphy (OPS): basalt (MORB, OIB)—chert (pelagic)—siliceous mudstone, siltstone and shale (hemipelagic)—trench sandstones (greywacke). The structural position and the lithology of Itmurundy rocks accord well with the model of formation of accretionary complexes at Pacific-type convergent margins, in particular, those in the western Pacific.

中文翻译：

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巴尔喀什北部地区Itmurundy增生复合体：地质构造，地层学和构造起源

摘要

巴尔喀什北部地区的Itmurundy带是太平洋型造山带。它具有复杂的地质结构，并拥有地幔，增生和造山后组合的岩石。增生协会的火山岩和沉积岩属于三组：Itmurundy（O _1-2），Kazyk（O _2-3）和Tyuretai（O ₃ -S ₁）。套件由构造不整合或三级断层分开：1）大型区域性断层；2）地幔断层将地幔和洋积岩分开；3）小断层将由海洋沉积物组成的包裹分开。Itmurundy Fm。（O _1-2）是岩性最强的变量，包括海洋玄武岩，浮游硅质t石，半潜质硅质泥岩和粉砂岩以及沟纹greywacke砂岩。每个包裹由硅质硅质泥岩组成，彼此分开，分别为^第二和^第三可能具有推力性质的有序断层，即它们是双相结构的一部分。双工结构的存在和Itmurundy Fm的高度变形。岩石是增生复合物的典型特征。所研究的火山岩和沉积岩的组合代表了整个海洋板块地层（OPS）：玄武岩（MORB，OIB）– t石（上层）–硅质泥岩，粉砂岩和页岩（中层）– nch沟砂岩（greywacke）。Itmurundy岩石的结构位置和岩性与太平洋类型的会聚边缘（尤其是西太平洋的边缘）增生复合物的形成模型非常吻合。